(dā'līt-sā'vĭng) Time during which clocks are set one hour or more ahead of standard time to provide more daylight at the end of the working day during late spring, summer, and early fall. First proposed by Benjamin Franklin, daylight saving time was instituted in various countries during both world wars in the 20th century and was made permanent in most of the United States beginning in 1973. Arizona, Hawaii, most of eastern Indiana, and certain US territories and possessions do not observe daylight saving time.